Effects of Mg deficiency and parathyroidectomy on gastrointestinal Ca transport in the rat

¹ Departments of Medicine and Epidemiology, Yale University School of Medicine, New Haven, Connecticut 06510

An open-ended, everted gut-sac technique was used to measure in vitro duodenal transfer of calcium in magnesium-deficient and pair-fed control animals with and without parathyroid glands. In contrast to previous studies employing the closed gut-sac technique in calcium-deprived animals, we were unable to demonstrate an effect of parathyroidectomy on the in vitro transport of calcium across the duodenum. Magnesium deficiency resulted in enhanced intestinal transport of calcium. These data confirm our previous studies and demonstrate that this effect of magnesium deficiency is linear over 2 hr of incubation. This enhancing effect of magnesium deficiency on gastrointestinal calcium transport was blocked by parathyroidectomy. The results of this study are consistent with the hypothesis that magnesium deficiency increases calcium transfer of the isolated everted gut-sac of rats by stimulating the secretion of parathyroid hormone.

Key Words: hyperparathyroidism • hypercalcemia • everted duodenal sac • duodenal calcium transport

Submitted on February 17, 1969